1. Field of the Invention
The present invention relates to a semiconductor device with semiconductor elements mounted on a microprocessed semiconductor substrate. The invention also relates to a manufacturing method of such semiconductor devices.
2. Description of the Related Art
Recently, LSI manufacturing technologies are applied to producing micromachines (micro-electro-mechanical systems or MEMS). In producing micromachines, a silicon substrate is subjected to a microprocessing process, and various semiconductor elements are mounted on the processed substrate. To micro-process a silicon substrate, use may be made of anisotropic etching, whereby minute recesses can be formed on the silicon substrate with accuracy.
JP-A-No. 2005-277380 discloses an LED package produced by micromachine manufacturing techniques. This conventional LED package is obtained by forming a recess on a silicon substrate by anisotropic etching and mounting an LED chip on the bottom face of the recess. The recess, formed by anisotropic etching, recedes from a (100) surface of the substrate and has a sloped side face constituted of a (111) surface of the substrate. A conductive layer is formed on the bottom face and the side face for electrical connection of the LED chip to an external circuit board, for example. The conductive layer may be formed by depositing a Cu layer on the bottom face and the side face (e.g. by sputtering), patterning the conductive layer by photolithography, and so on.
To perform the above-mentioned patterning, a resist layer is formed over the deposited Cu layer by application of a suitable resist material, and the obtained resist layer is exposed to light via a photomask. At this stage, when the portion of the resist layer formed on the side face is irradiated, the light may reach the underlying Cu layer through the resist layer and be reflected by the Cu layer. The reflected light may travel toward the bottom face of the recess and irradiate a portion of the resist layer formed over the bottom face. Such exposure of light (“secondary exposure”) with respect to the resist layer, however, is not intended and may cause an inconvenience as follows.
Supposing that the recess formed in the substrate has two mutually opposing side faces, light reflected on the respective side faces may irradiate a region of the resist layer on the bottom surface in an overlapping manner. When the resist layer is of a positive type, the region of the resist layer subjected to the overlapped light exposure may be unduly removed in a developing process. Unfavorably, the use of such an improperly patterned resist layer for a subsequent process (such as electrolytic plating for forming an additional conductive layer on the underlying Cu layer, using the resist layer as a mask) will form undesired conductive paths in the final product, which may be a cause of a malfunction such as a short circuit.